Maximizing Conversion of Surface Click Reactions for Versatile Molecular Modification on Metal Oxide Nanowires
Maximizing Conversion of Surface Click Reactions for Versatile Molecular Modification on Metal Oxide Nanowires
复制标题
最大限度地提高表面点击反应的转化率，以实现金属氧化物纳米线的多功能分子修饰
DOI：
10.1021/acs.langmuir.1c00106
复制
发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Yanagida Takeshi
中科院分区：
文献类型：
--
作者：
Yamaguchi Rimon;Hosomi Takuro;Otani Masaya;Nagashima Kazuki;Takahashi Tsunaki;Zhang Guozhu;Kanai Masaki;Masai Hiroshi;Terao Jun;Yanagida Takeshi
金属氧化物纳米结构上的点击反应(例如，惠氏环加成反应)为各种应用提供了一种通用和强大的表面分子修饰，因为它们在广泛的分子底物上形成强大的共价键。这项研究报告了一种合理的策略，通过监控单晶氧化锌纳米线上的表面点击反应的进展来最大化表面点击反应的转化率。利用P偏振多角度入射分辨光谱(PMAIRS)和傅里叶变换红外光谱(FT-IR)研究了叠氮自组装单分子膜(SAM)在单晶氧化锌纳米线上的反应过程。虽然系统地考察了不同的反应参数，包括铜(I)催化剂的浓度、三氮唑配体、溶剂和目标炔烃的浓度，但纳米线表面10-30%的末端叠氮化物仍然没有反应。依赖温度的FT-IR测试表明，这种未反应的残留叠氮化物恶化了纳米线分子层的热稳定性。为了克服在纳米结构表面观察到的点击反应的转化限制，我们考虑了紧密堆积的SAM反应点周围的空间位阻，然后将叠氮部分分散到甲基封端的SAM中。混合SAM法显著提高了叠氮转化率，转化率接近100%。这种反应方法能够在金属氧化物纳米线阵列上构建空间图案化的分子表面修饰，而不会产生有害的未反应叠氮基。
Click reactions (e.g., Huisgen cycloaddition) on metal oxide nanostructures offer a versatile and robust surface molecular modification for various applications because they form strong covalent bonds in a wide range of molecular substrates. This study reports a rational strategy to maximize the conversion rate of surface click reactions on single-crystalline ZnO nanowires by monitoring the reaction progress. p-Polarized multiple-angle incidence resolution spectrometry (pMAIRS) and Fourier-transformed infrared (FT-IR) spectroscopy were employed to monitor the reaction progress of an azide-terminated self-assembled monolayer (SAM) on single-crystalline ZnO nanowires. Although various reaction parameters including the concentration of Cu(I) catalysts, triazolyl ligands, solvents, and target alkynes were systematically examined for the surface click reactions, 10–30% of terminal azide on the nanowire surface remained unreacted. Temperature-dependent FT-IR measurements revealed that such unreacted residual azides deteriorate the thermal stability of the nanowire molecular layer. To overcome this observed conversion limitation of click reactions on nanostructure surfaces, we considered the steric hindrance around the closely packed SAM reaction points, then experimented with dispersing the azide moiety into a methyl-terminated SAM. The mixed-SAM method significantly improved the azide conversion rate to almost 100%. This reaction method enables the construction of spatially patterned molecular surface modifications on metal oxide nanowire arrays without detrimental unreacted azide groups.